1. Field of the Invention
The present invention relates to a fluid supply apparatus. In particular, the present invention relates to a fluid supply apparatus comprising a port block which is movable along a guide rail having a fluid supply passages provided therein, wherein a fluid is supplied to the port block at an arbitrary position on the guide rail.
2. Description of the Related Art
A slide joint has been hitherto known as such a fluid supply apparatus. According to Japanese Laid-Open Utility Model Publication No. 1-150295, a slide joint includes a pipe provided with a long groove formed in the longitudinal direction of the pipe. A flexible seal belt is fitted to the long groove, and the seal belt is pressed by the internal pressure to close the long groove. Further, the slide joint includes a pressing member which penetrates through the long groove to separate the seal belt from the long groove. The pressing member is installed to the inner circumference of a cylindrical member which is externally fitted slidably with respect to the outer circumferential surface of the pipe. The cylindrical member has a gap centrally provided therein. Opposite ends of the cylindrical member are closed tightly.
In FIGS. 19 and 20, the conventional slide joint 1 comprises a pipe 2 having high rigidity, a flexible seal belt 4 fitted to a long groove 3 formed in the longitudinal direction of the pipe 2, a cylindrical member 5, and a pressing member 6. The cylindrical member 5 presses the seal belt 4 by the internal pressure to close the long groove 3. The cylindrical member 5 is slidably fitted to the outer circumferential surface of the pipe 2. The cylindrical member 5 has a gap centrally provided therein. Opposite ends of the cylindrical member 5 are closed tightly. The pressing member 6 is provided on the inner circumference of the cylindrical member 5 and penetrates through the long groove 3 to separate the seal belt 4 from the long groove 3.
The gap 7 is provided between the cylindrical member 5 and the outer circumference of the pipe 2. Further, packings 9 are installed to fitting sections 8 at the opposite ends of the cylindrical member 5. The packings 9 tightly contact with the outer circumferential surface of the pipe 2 so that the interior of the gap 7 is kept in an air-tight manner. Reference numeral 10 indicates a connector. A rubber hose 11 connected to an unillustrated spray gun is screw-fastened thereto.
As for the pressing member 6, the upper surface of a connecting section 12 penetrating through the long groove 3 is fixed by screws 13 to the inner circumferential surface of the cylindrical member 5. A pressing surface 14 is curved downwardly in parallel to the long groove 3 and formed on the lower surface of the connecting section 12. Guide surfaces 15 of the pressing surface 14 are separated from each other by the width of the seal belt 4 (see FIG. 20). A pair of support sections 16, 16 extend longitudinally on both sides of the pressing member 6. The support sections 16, 16 are joined to each other by joined sections 17, 17 at mutually corresponding forward ends respectively. An opening 18 is formed between the pressing member 6 and the joined section 17.
The slide joint 1 constructed as described above is used as follows. That is, when the cylindrical member 5 makes make sliding movement along the pipe 2, the seal belt 4 is interposed between the opposite ends of the cylindrical member 5 and the support sections 16 of the pressing member 6. The upper surface of the seal belt 4 is pressed by the pressing surface 14 of the pressing member 6, and it is separated from the long groove 3. Accordingly, the compressed air, which flows into the pipe 2, is fed via the opening 18 and the long groove 3, and it is supplied from the gap 7 to the rubber hose 11.
In the conventional slide joint 1 described above, the pressing member 6 is fitted and inserted into the long groove 3 to prevent the cylindrical member 5 from rotation. However, if the load in the circumferential direction is applied to the cylindrical member 5, the connecting section 12 of the pressing member 6 abuts against the inner surface of the long groove 3, and an excessive sliding friction is generated during the reciprocating movement of the cylindrical member 5. As a result, the cylindrical member 5 cannot make the reciprocating movement smoothly.
Further, it is difficult for the pressing member 6 to uniformly press the upper surface of the seal belt 4, due to the load applied to the cylindrical member 5. Thus, the seal belt 4 may not be deformed corresponding to the shape of the pressing surface 14. Therefore, the compressed air in the pipe 2 does not flow into the gap 7 of the cylindrical member 5, and the compressed air is not supplied to the rubber hose 11 under a predetermined condition.
Further, when the slide joint 1 is attached to a pneumatic pressure apparatus, additional parts for attaching the slide joint 1 and the pneumatic pressure apparatus are required, because the outer contour of the slide joint 1 is columnar. Therefore, the number of parts is increased, the structure is complicated, and the production cost is increased.
A general object of the present invention is to provide a fluid supply apparatus which has a simple structure, which favorably absorbs the load, and which makes it possible to reduce the production cost.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.